Solar collector are used to collect the solar heat at a particular point to harness it in a useful manner. A solar collector gathers solar energy during the day time which is used either in night lights or for any other purpose. A solar collector consists of a flat box and it contains of three main parts, , tubes which carry a coolant a transparent cover and an insulated back plate. A solar collector works on the principle of Green house effect.
The solar radiation are incident on the transparent surface of the solar collector and then it is transmitted through though the surface. The inside portion of a solar collector is made evacuated. And after the energy is collected it is used to heat the coolant which is inside the tubes. To avoid any kind of heat losses the tubes are made of copper and are painted black.
METHODS OF USING SOLAR ENERGY:
There are many ways in which solar energy can be collected from the incident radiation of the sun. Some of them are listed below:
- Photo voltaic (Pv)
- Solar thermal
- Un-glazed perforated plate collectors
- Glazed flat-plate solar collectors
- Parabolic dish systems
- Air based solar collectors
- Back-pass solar collectors
- Concentrating solar collectors
- Batch solar collectors
- Solar cookers
Some of the methods are discussed below
PHOTO VOLTAIC METHOD:
Photo voltaic works on the method of converting sunlight into electricity with the use of a semiconductor. In photo voltaic cell when the light strikes the cell then a small amount of energy is absorbed by it which is transferred to the semiconductors which has free electrons in it which are set in motion by the heat which allows the flow of current.
The visible portion of the light is absorbed by the photo voltaic cell. Photo voltaic cell are collected on panels to supply electricity to power grid. The pv cell are connected to a source which can convert DC current to AC current which is basically an inverter.
SOLAR THERMAL METHOD:
Solar thermal binds up all the categories such as solar hot water panel, solar heater, solar thermal collector etc. Solar thermals works on very simple principle that when light falls on any object after some time it becomes hot. The same principle with some modification is used in different types of solar thermal.
The upper coating of the solar thermal is made of special material to maximize the amount of heat absorbed apricus which can increase the absorption power by 95%, tinox etc.
BATCH SOLAR COLLECTOR METHOD:
Batch collectors have a flat plate collector , a reflector which is used to concentrate the heat radiation of the sun on the surface of the tank. In batch solar collector the storage tank and the absorber are a single unit which make it simple in construction and less in cost. They are mostly used in cold countries to heat the water.
Solar cooker consists of a concentrator to increase the availability of solar energy inside the cooker and has a insulation cover to reduce the heat losses. Solar cooker has a oven type cavity in which the food to be cooked is placed which has a temperature of about 200-300F and sometimes it also reaches around 450 degree F when the sunlight is intense.
Solar cooker are the best way which can be used as an alternative in place of LPG in day time so that the fuel energy can be saved. Making solar cookers and using them can be a fun and educational school project.
ADVANTAGES OF A SOLAR COLLECTOR:
- Solar collector have a larger surface area which helps in more collection of solar energy.
- Solar collectors demands less investment which make it more economical.
- Solar collector once installed are needed to be repaired or checked after a long period of time which decreases the maintenance cost.
- Solar collector have a simplified installation and system integration.